Friction linings, particularly organically bonded friction linings, are nowadays frequently subjected to high thermal loading. Since they are supposed to produce a high braking force, even in the first braking process, the friction surface is thermally treated by pressing it against a hot plate (scorching) or with a gas flame or the like in order to prevent green fading (DE-A 4032182). The decomposition products of the organic bonding agent in the region close to the surface, which are responsible for the reduction in the coefficient to friction, are thus removed.
In the scorching process, e.g. 20 ground and post-hardened friction linings are pressed simultaneously against a hot plate at up to 750.degree. C.
The heating process can be interrupted a number of times by ventilation in order to facilitate the removal of the decomposition products. The linings are subsequently cooled by pressing against a cooling plate. The back plates of the friction linings are then generally cleaned and coated.
It is disadvantageous in the known method that the friction surface is subjected to the maximum temperature even when it is pressed for the first time against the heating plate. Sealing of the surface can thereby occur which prevents the escape of the decomposition products. The temperature of the heating plate can also be maintained constant over its entire area only with great difficulty. Temperature variations of 15K and more are quite common. The friction linings of a scorched batch can thus have a different wear or coefficient of friction.
The treatment time for the scorching is naturally dependent on the shape and material of the friction lining, it is thus practically impossible to integrate the known scorching process into a continuous manufacturing method.